540
FXUS65 KBYZ 311516
AFDBYZ
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BILLINGS MT
916 AM MDT MON MAR 31 2025
KEY MESSAGES
- PERIODS OF HEAVY MOUNTAINS SNOW WILL BEGIN TO IMPACT THE WESTERN
MOUNTAINS THIS EVENING THROUGH WEDNESDAY. TOTALS WILL BE BETWEEN
8-16".
- PERIODS OF HEAVY SNOW POSSIBLE IN THE BIGHORNS BEGINNING
TUESDAY EVENING, WITH 7-14 INCHES OF SNOW POSSIBLE.
- COOL AND UNSETTLED CONDITIONS PERSIST FOR THE SECOND HALF OF THE
WEEK WITH ADDITIONAL RAIN/SNOW CHANCES POSSIBLE.
DISCUSSION
TODAY THROUGH WEDNESDAY AFTERNOON...
SHORTWAVE RIDGE WILL BEGIN TO DEPART THE REGION THIS MORNING.
OVERRUNNING ENERGY AND MOISTURE CONTINUES OVER THE SOUTHWESTERN
MOUNTAINS, INCLUDING LOCATIONS SUCH AS COOKE CITY WHERE A FEW
INCHES OF SNOW ARE POSSIBLE. OUTSIDE OF THE MOUNTAINS, EXPECT DRY
CONDITIONS TO PREVAIL INTO THIS EVENING. HIGH TEMPERATURES WILL BE
IN THE 40S AND 50S TODAY AND TUESDAY.
A DEEPENING UPPER TROUGH IS SHOWN BY MODELS MOVING THROUGH THE
WESTERN U.S., TODAY THROUGH WEDNESDAY. MODELS ARE STILL SHAKY ON
SPECIFICS BUT THE GENERAL PATTERN IS A DEVELOPING UPPER LOW SETTING
UP OVER THE NORTHERN ROCKIES AND SURFACE LOW AROUND THE CENTRAL
PLAINS. CONFIDENCE IN PRECIPITATION ACCUMULATIONS REMAINS
MODERATE, WHILE CONFIDENCE IN TEMPERATURES IS HIGH. CONFIDENCE FOR
TIMING WITH THE SYSTEM IS MODERATE TO HIGH, WITH MODELS SHOWING
THE UPPER LEVEL TROUGH SPREADING OVER THE REGION BY TUESDAY
MORNING. THE PLACEMENT AND TIMING OF THE UPPER LOW IS STILL
UNCLEAR, THOUGH THE LATEST DETERMINISTIC MODELS ARE IN MODERATE
AGREEMENT OF THIS OCCURRING OVER CENTRAL MONTANA DURING THE DAY
TUESDAY.
THE SIGNIFICANCE OF THE UPPER LOWS PLACEMENT AND DEVELOPMENT IS
CRUCIAL TO POTENTIAL IMPACTS TO THE FORECAST AREA TUESDAY THROUGH
WEDNESDAY. AN INTERESTING NOTE WITH THE LATEST MODEL RUNS IS THE
DEPICTION OF A TROWAL OVER THE SOUTHEAST AND INTO OUR
NORTHWESTERN ZONES. THETA-E ANALYSIS BETWEEN 700-500MB ALSO SHOWS
INDICATIONS OF THIS. THE POTENTIAL RESULTS FROM A TROWAL WOULD BE
NOTABLE, WITH HEAVIER PRECIPITATION RATES AND HIGHER
ACCUMULATIONS. THE CURRENT FORECAST HAS PRECIP TYPE AS RAIN ACROSS
THE LOWER ELEVATIONS BEGINNING THIS EVENING. A TRANSITION TO A
RAIN/SNOW MIX WILL BEGIN EARLY TUESDAY WITH OVERNIGHT TEMPERATURES
AROUND OR BELOW FREEZING. A TRANSITION BACK TO RAIN WILL OCCUR
DURING THE DAY TUESDAY BEFORE GOING BACK TO A RAIN/SNOW MIX AND
THEN ALL SNOW TUESDAY NIGHT.
WITH 8-16 INCHES OF SNOWFALL POSSIBLE IN THE ABSAROKA/BEARTOOTH,
AND CRAZY MOUNTAINS, A WINTER STORM WARNING WILL GO INTO EFFECT AT
6PM THIS EVENING AND LAST UNTIL 6PM WEDNESDAY. A WINTER STORM
WATCH GOES INTO EFFECT FOR THE BIGHORN MOUNTAINS AT 6PM TUESDAY
EVENING, WITH 7-14 INCHES OF SNOW POSSIBLE. THOSE PLANNING TO GO
INTO THE BACKCOUNTRY SHOULD BE PREPARED FOR PERIODS OF HEAVY AND
WET SNOWFALL.
AS THE UPPER TROUGH APPROACHES THIS EVENING, CONVECTIVE
INSTABILITY WILL INCREASE WITH UPPER LEVEL DIFFLUENCE. SEVERAL
HUNDRED JOULES OF CAPE ARE SHOWN OVER THE WESTERN ZONES AS WELL AS
THE SOUTHEAST BY THE LATEST RUN OF THE HREF. A FEW WEAK
THUNDERSTORMS WILL BE POSSIBLE, THOUGH SIGNIFICANT IMPACTS ARE NOT
EXPECTED.
UPPER LOW SHIFTS EAST INTO WEDNESDAY, ALLOWING FOR CONTINUED
UPSLOPE FLOW INTO THE MOUNTAINS AND FOOTHILLS. SNOWFALL AMOUNTS IN
THE FOOTHILLS RANGE FROM 2-6 INCHES WITH HIGHER AMOUNTS IN THE
BEARTOOTH, RED LODGE, AND MELVILLE FOOTHILLS. LOWER AMOUNTS
(CLOSER TO 2-4 INCHES) IN THE SHERIDAN FOOTHILLS. AMOUNTS QUICKLY
DECREASE AWAY FROM THE FOOTHILLS WITH UP TO AN INCH OF SNOWFALL
POSSIBLE OUT TO BILLINGS, TUESDAY NIGHT THROUGH WEDNESDAY.
MATOS
WEDNESDAY NIGHT THROUGH SUNDAY...
PRECIPITATION DIMINISHES FROM NORTH TO SOUTH WEDNESDAY NIGHT AS
WEAK SUBSIDENCE MOVES IN BEHIND THE UPPER LOW EXITING THE REGION
TO THE EAST. THE DRIER CONDITIONS ARE SHORT-LIVED HOWEVER, AS A
SHORTWAVE AND ASSOCIATED COLD FRONT DROP IN FROM THE NORTHWEST ON
THURSDAY, BRINGING COOLER CONDITIONS AND RAIN/SNOW CHANCES
(30-60%) INTO FRIDAY. AT THIS TIME, PRECIPITATION TOTALS OF 0.25
INCHES OR LESS ARE FORECAST, WITH A FEW INCHES OF SNOW
ACCUMULATION IN THE MOUNTAINS AND LIGHT AMOUNTS IN THE LOWER
ELEVATIONS. DRIER AND WARMER CONDITIONS BEGIN BUILDING INTO THE
REGION OVER THE WEEKEND. CONFIDENCE IS HIGH FOR WARMER AND DRIER
CONDITIONS PERSISTING INTO NEXT WEEK AS STRONG RIDGING DEVELOPS
OVER THE WESTERN US.
TEMPERATURES ARE FORECAST TO BE NEAR OR BELOW NORMAL THROUGH MOST
OF THE LONG TERM. HIGH TEMPERATURES LOOK TO RANGE FROM THE 30S AND
40S THURSDAY AND FRIDAY (10 TO 15 DEGREES BELOW NORMAL), WARMING
INTO THE 40S AND 50S FOR SATURDAY AND SUNDAY. STP
AVIATION
UPDATED AT 15Z:
FOG (SOME OF IT DENSE) IS DISSIPATING, BUT AREAS OF LOW STRATUS
W/ MVFR TO IFR CEILINGS WILL LINGER TO MIDDAY OR EARLY AFTERNOON,
ESPECIALLY IN UPSLOPE AREAS NORTHWEST OF KBIL (INCLUDING KHWQ).
SCATTERED SHOWERS, AND PERHAPS A FEW WEAK THUNDERSTORMS, WILL
SPREAD IN FROM THE SOUTHWEST ACROSS WESTERN AND CENTRAL AREAS
DURING THE AFTERNOON AND EVENING HOURS. LOCALIZED MVFR AND GUSTY
WINDS ARE POSSIBLE WITH THE STRONGEST ACTIVITY. THERE IS A RISK OF
FOG/STRATUS IN THE FAR SOUTHEAST CORNER OF MT TONIGHT, POSSIBLY
IMPACTING KBHK WITH IFR OR LESS, BUT THE CHANCES OF FOG IMPACTING
A TAF SITE ARE LOW (10%). JKL
PRELIMINARY POINT TEMP/POPS
TDY TUE WED THU FRI SAT SUN
-------------------------------------------------------
BIL 053 034/049 033/047 029/047 029/043 026/051 028/058
2/R 33/O 56/O 25/O 54/S 21/U 00/U
LVM 051 032/043 031/043 028/044 027/041 024/050 027/056
4/T 55/S 65/S 35/S 53/S 11/U 00/U
HDN 056 031/049 031/046 028/048 027/043 024/052 026/057
1/B 23/O 57/O 25/O 44/S 22/S 00/U
MLS 052 033/046 031/043 028/047 028/043 024/050 026/054
0/B 35/R 53/O 12/R 32/S 11/U 00/U
4BQ 051 033/045 031/041 027/046 028/041 024/047 026/052
1/B 23/O 66/S 22/R 32/S 21/U 00/U
BHK 046 029/042 026/039 022/044 024/039 019/045 021/049
0/N 36/O 65/S 22/O 32/S 11/U 00/U
SHR 054 027/046 026/042 022/046 024/039 020/047 022/053
2/W 24/O 78/O 25/O 45/S 32/O 10/U
BYZ WATCHES/WARNINGS/ADVISORIES
MT...WINTER STORM WARNING IN EFFECT FROM 6 PM THIS EVENING TO 6 PM
MDT WEDNESDAY FOR ZONES 67-68.
WINTER STORM WATCH IN EFFECT FROM TUESDAY EVENING THROUGH
WEDNESDAY AFTERNOON FOR ZONE 171.
WY...WINTER STORM WATCH IN EFFECT FROM TUESDAY EVENING THROUGH
WEDNESDAY AFTERNOON FOR ZONE 198.
WEATHER.GOV/BILLINGS
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